#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
int main(){
	int n,m,q,f;cin>>n>>m>>q>>f;
	vvi in(q,vi(3));
	rep(i,q)rep(j,3)cin>>in[i][j];
	vvi dp(n+1,vi(m+1,inf));
	dp[0][0]=0;
	rep(k,q)for(int i=n;i>=0;i--)for(int j=m;j>=0;j--)if(i+in[k][0]<=n&&j+in[k][1]<=m)dp[i+in[k][0]][j+in[k][1]]=min(dp[i+in[k][0]][j+in[k][1]],dp[i][j]+in[k][2]);
	int mi=inf;
//	rep(i,n+1){rep(j,m+1)cout<<" "<<dp[i][j];cout<<endl;}
	rep(i,n+1)rep(j,m+1)if(dp[i][j]!=inf)mi=min(mi,dp[i][j]+(n-i+m-j)*f);
	cout<<mi<<endl;
}